Photonic integrated circuits (PICs; also called photonic chips) are often formed using photolithographic techniques, wherein dopants (such as lasing species and index-of-refraction modifiers) are diffused into a glass or silicon substrate through a mask. Some PICs include surface features such as diffraction gratings. Lasers, optical couplers, resonators, add-drop ports, interferometers, and the like can be manufactured into PICs. Some hybrid optical-electrical PICs also include electronic circuits. A large number of such photonic integrated circuits can be simultaneously fabricated onto a wafer substrate, then tested and diced into individual PICs.
The telecommunications industry commonly uses optical fibers to transmit large amounts of data in a short time. One common light source for optical-fiber communications systems is a laser formed using erbium-doped glass. One such system uses erbium-doped glass fibers to form a laser that emits at a wavelength of about 1.536 micrometer and is pumped by an infrared source operating at a wavelength of about 0.98 micrometer. One method usable for forming waveguides in a substrate is described in U.S. Pat. No. 5,080,503 issued Jan. 14, 1992 to Najafi et al., which is hereby incorporated by reference. A phosphate glass useful in lasers is described in U.S. Pat. No. 5,334,559 issued Aug. 2, 1994 to Joseph S. Hayden, which is also hereby incorporated by reference. An integrated optic laser is described in U.S. Pat. No. 5,491,708 issued Feb. 13, 1996 to Malone et al., which is also hereby incorporated by reference.
Exemplary patents describing various PICs include the following three patents and patent application invented by Bendett and Whaley et al.
United States Patent Publication 20030185514 by Bendett and Whaley published on Oct. 2, 2003 with the title “Method and apparatus for tapping a waveguide on a substrate,” and is incorporated herein by reference. In Patent Publication 20030185514, Bendett et al. describe an integrated photonic apparatus that includes a glass substrate having a major surface, a first waveguide segment and a second waveguide segment, and a optical tap or port that extracts a portion of the light from the first waveguide segment into the second waveguide segment, and emits that light from a surface of the substrate. In some embodiments, a wavelength-selective evanescent coupler and/or a wavelength-selective optical diffraction grating perform a selection of one or more wavelengths to exit from the port.
U.S. Pat. No. 6,330,388 issued to Bendett et al. on Dec. 11, 2001 with the title “Method and apparatus for waveguide optics and devices,” and is incorporated herein by reference. In U.S. Pat. No. 6,330,388, Bendett et al. describe optical structures and a method for producing tunable waveguide lasers. In one embodiment, a waveguide is defined within a glass substrate doped with a rare-earth element or elements by ion diffusion. Feedback elements such as mirrors or reflection gratings in the waveguide further define a laser-resonator cavity so that laser light is output from the waveguide when pumped optically or otherwise.
U.S. Pat. No. 6,493,476 issued to Bendett on Dec. 10, 2002 with the title “Apparatus and method for integrated photonic devices having gain and wavelength-selectivity,” and is incorporated herein by reference. In U.S. Pat. No. 6,493,476, Bendett describes an integrated photonic apparatus that includes a glass substrate having a major surface, wherein the glass substrate includes a plurality of regions, each region having a different index of refraction, including a first region having a first index of refraction and a second region having a second index of refraction lower than the first index of refraction, and a first waveguide formed along the major surface of the substrate, wherein the first waveguide has a higher index of refraction than an intrinsic index of refraction of adjacent portions of the substrate, and wherein the first waveguide passes through the first region and through the second region of the glass substrate.
U.S. Pat. No. 6,813,405 issued to Bendett and Whaley on Nov. 2, 2004 with the title “Compact apparatus and method for integrated photonic devices having folded directional couplers,” and is incorporated herein by reference. In U.S. Pat. No. 6,813,405, Bendett et al. describe an integrated photonic apparatus that includes a glass substrate having a major surface, a first waveguide segment and a second waveguide segment, and a folded evanescent coupler connecting the first waveguide segment to the second. The folded evanescent coupler is formed by a first length of the first waveguide segment and an equivalent length portion of the second waveguide running parallel and adjacent to the first waveguide segment. The first length is substantially equal to one half of an evanescent-coupler length needed to transfer a first wavelength in a non-folded evanescent coupler. A reflector (e.g., dielectric mirror that is highly reflective to light of the first wavelength and also highly transmissive to light of a second wavelength) is located at an end of the folded evanescent coupler. The first length is selected to transfer substantially all light of a first wavelength.
U.S. Pat. No. 4,575,181 (hereinafter, “Ishikawa”), titled “OPTICAL FIBER ASSEMBLY WITH CLADDING LIGHT SCATTERING MEANS”, issued Mar. 11, 1986, and is incorporated herein by reference. Ishikawa describes an optical fiber having a core and a cladding that is covered with a protecting film. The film is removed in a predetermined region extending from the end face of the optical fiber along the optical fiber, and the cladding is exposed. The surface of the exposed cladding is formed with a rough surface, and a laser beam which is transmitted to the cladding is scattered externally from the rough surface. The optical fiber is mounted on the hollow holder, and the rough surface of the cladding is disposed in the holder. The beam component scattered externally from the rough surface is absorbed by the light absorbing layer on the inner surface of the holder.
The present invention can also be used with or in the inventions described in the following patents and patent applications: U.S. Pat. No. 5,336,366 (hereinafter, “Cain et al.”), titled “NEW DRY ETCH TECHNIQUE”, issued Aug. 9, 1994; U.S. Pat. No. 6,905,627 (hereinafter, “Wei et al.”), titled “ETCHING METHOD FOR FABRICATING HIGH QUALITY OPTICAL FIBER PROBE”, issued Jun. 14, 2005; U.S. Pat. No. 5,136,818 (hereinafter, “Bramson”), titled “METHOD OF POLISHING OPTICAL FIBER”, issued Aug. 11, 1992; U.S. Pat. No. 4,894,127 (hereinafter, “Wong et al.”), titled “METHOD FOR ANODIZING ALUMINUM”, issued Jan. 16, 1990; and U.S. Pat. Nos. 7,429,734, 7,471,705, and 7,539,231; U.S. patent application Ser. No. 11/688,854 (which issued as U.S. Pat. No. 7,835,608 on Nov. 16, 2010), and Ser. No. 12/624,327 (which issued as U.S. Pat. No. 8,441,718 on May 14, 2013); and U.S. Provisional Patent Application Ser. No. 61/263,736; which are each incorporated herein by reference.
The present invention can also be used with or in the inventions described in the following patents and patent applications:
U.S. patent application Ser. No. 11/342,336 by Andrew J. W. Brown et al. filed Jan. 26, 2006, titled “APPARATUS AND METHOD FOR SPECTRAL-BEAM COMBINING OF HIGH-POWER FIBER LASERS” (U.S. Pat. No. 7,199,924);
U.S. patent application Ser. No. 11/420,729 by Fabio Di Teodoro et al. filed May 26, 2006, titled “FIBER-OR ROD-BASED OPTICAL SOURCE FEATURING A LARGE-CORE, RARE-EARTH-DOPED PHOTONIC-CRYSTAL DEVICE FOR GENERATION OF HIGH-POWER PULSED RADIATION AND METHOD” (U.S. Pat. No. 7,391,561);U.S. patent application Ser. No. 11/567,740 by John D. Minelly et al. filed Dec. 7, 2006, titled “APPARATUS AND METHOD FOR AN ERBIUM-DOPED FIBER FOR HIGH PEAK-POWER APPLICATIONS” (U.S. Pat. No. 7,570,856);U.S. patent application Ser. No. 11/565,619 by Matthias P. Savage-Leuchs filed Nov. 30, 2006, titled “METHOD AND APPARATUS FOR OPTICAL GAIN FIBER HAVING SEGMENTS OF DIFFERING CORE SIZES” (U.S. Pat. No. 7,768,700);U.S. patent application Ser. No. 12/053,551 by Fabio Di Teodoro et al. filed Mar. 21, 2008, titled “HIGH-POWER, PULSED RING FIBER OSCILLATOR AND METHOD” (U.S. Pat. No. 7,876,803);U.S. patent application Ser. No. 12/054,375 by Eric C. Honea et al. filed Mar. 24, 2008, titled “PULSE-ENERGY-STABILIZATION APPROACH AND FIRST-PULSE-SUPPRESSION METHOD USING FIBER AMPLIFIER” (U.S. Pat. No. 7,876,498);U.S. patent application Ser. No. 12/165,651 by Tidwell, et al. that issued May 15, 2012 with the title “METHOD AND APPARATUS FOR SPECTRAL-BEAM COMBINING OF FANNED-IN LASER BEAMS WITH CHROMATIC-DISPERSION COMPENSATION USING A PLURALITY OF DIFFRACTIVE GRATINGS” (U.S. Pat. No. 8,179,594);U.S. patent application Ser. No. 12/169,628 by John D. Minelly filed Jul. 8, 2008, titled “MICRO-STRUCTURED FIBER PROFILES FOR MITIGATION OF BEND-LOSS AND/OR MODE DISTORTION IN LMA FIBER AMPLIFIERS, INCLUDING DUAL-CORE EMBODIMENTS” (U.S. Pat. No. 7,924,500);U.S. patent application Ser. No. 12/050,937 titled “A METHOD AND MULTIPLE-MODE DEVICE FOR HIGH-POWER SHORT-PULSE-LASER ABLATION AND CW CAUTERIZATION OF BODILY TISSUES” filed Mar. 18, 2008 by Jonathon Wells et al. (U.S. Pat. No. 8,202,268);U.S. patent application Ser. No. 12/952,190 by Matthias P. Savage-Leuchs et al. filed Nov. 22, 2010, titled “Q-SWITCHED OSCILLATOR SEED-SOURCE FOR MOPA LASER ILLUMINATOR METHOD AND APPARATUS” (U.S. Pub. 2011/0122895, which issued as U.S. Pat. No. 8,934,509 on Jan. 13, 2015);U.S. patent application Ser. No. 13/085,354 by Matthias P. Savage-Leuchs filed Apr. 12, 2011, titled “HIGH-POWER LASER SYSTEM HAVING DELIVERY FIBER WITH NON-CIRCULAR CROSS SECTION FOR ISOLATION AGAINST BACK REFLECTIONS” (U.S. Pat. No. 8,736,953);U.S. patent application Ser. No. 13/085,411 by Matthias P. Savage-Leuchs et al. filed Apr. 12, 2011, titled “HIGH BEAM QUALITY AND HIGH AVERAGE POWER FROM LARGE-CORE-SIZE OPTICAL-FIBER AMPLIFIERS” (U.S. Pub. 2011/0249320, which issued as U.S. Pat. No. 8,830,568 on Sep. 9, 2014);U.S. patent application Ser. No. 13/085,462 by Matthias P. Savage-Leuchs et al. filed Apr. 12, 2011, titled “SIGNAL AND PUMP MODE-FIELD ADAPTOR FOR DOUBLE-CLAD FIBERS AND ASSOCIATED METHOD” (U.S. Pub. 2011/0249321, which issued as U.S. Pat. No. 8,767,286 on Jul. 1, 2014);U.S. patent application Ser. No. 12/854,868 by Tolga Yilmaz et al. filed Aug. 11, 2010, titled “IN-LINE FORWARD/BACKWARD FIBER-OPTIC SIGNAL ANALYZER” (U.S. Pub. 2011/0091155, which issued as U.S. Pat. No. 8,755,649 on Jun. 17, 2014);U.S. patent application Ser. No. 12/793,508 by Yongdan Hu filed Jun. 3, 2010, titled “METHOD AND APPARATUS FOR IN-LINE FIBER-CLADDING-LIGHT DISSIPATION” (U.S. Pat. No. 8,355,608);U.S. patent application Ser. No. 13/085,465 by Eric C. Honea et al. filed Apr. 12, 2011, titled “BEAM DIAGNOSTICS AND FEEDBACK SYSTEM AND METHOD FOR SPECTRALLY BEAM-COMBINED LASERS” (U.S. Pat. No. 8,411,712);U.S. patent application Ser. No. 12/861,773 by Yongdan Hu et al. filed Aug. 23, 2010, titled “OPTICAL-FIBER ARRAY METHOD AND APPARATUS” (U.S. Pat. No. 8,503,840);U.S. patent application Ser. No. 14/086,744 by Eric C. Honea et al. filed Nov. 21, 2013, titled “FIBER AMPLIFIER SYSTEM FOR SUPPRESSION OF MODAL INSTABILITIES AND METHOD” (which issued as U.S. Pat. No. 9,214,781 on Dec. 15, 2015);U.S. patent application Ser. No. 13/987,265 by Eric C. Honea et al. filed Feb. 18, 2014, titled “APPARATUS AND METHOD FOR FIBER-LASER OUTPUT-BEAM SHAPING FOR SPECTRAL BEAM COMBINATION” (which issued as U.S. Pat. No. 9,366,872 on Jun. 14, 2016);U.S. Provisional Patent Application 61/877,796 by Andrew Xing et al. filed Sep. 13, 2013, titled “APPARATUS AND METHOD FOR A DIAMOND SUBSTRATE FOR A MULTI-LAYERED DIELECTRIC DIFFRACTION GRATING”;U.S. Provisional Patent Application 61/854,277 filed Apr. 30, 2014 by Yongdan Hu et al. titled “SYSTEM AND METHOD FOR HIGH-POWER, HIGH-STRAYLIGHT-LOAD FIBER ARRAY”; each of which is incorporated herein by reference.
U.S. Pat. No. 6,295,404 to Takenori Ichigi et al. (hereinafter, “Ichigi et al.”) titled “OPTICAL FIBER ARRAY”, issued Sep. 25, 2001, and is incorporated herein by reference. Ichigi et al. describe an optical fiber array that includes a V-groove substrate for housing an uncovered glass fiber section formed at an end portion of an optical fiber contained therein. A lower covered section housing portion houses a covered section of the optical fiber and is formed to be deeper than the V-groove forming portion. An optical fiber is disposed so that the uncovered glass fiber section is housed in the V groove and the covered section is housed in the lower covered section housing portion. A lid substrate is composed of a glass fiber protective portion covering an upper surface of the uncovered glass fiber section and an upper covered section housing portion houses a covered section of the optical fiber. The upper covered section housing portion is formed to be deeper than the glass fiber protective portion and is disposed on the V-groove substrate. A resin is filled in the gaps among the V-groove substrate, the optical fiber, and the lid substrate and cured to give a unitary optical fiber array.
U.S. Pat. No. 7,149,399 to Martin G. Meder et al. (hereinafter, “Meder et al.”) titled “GLASS BONDED FIBER ARRAY AND METHOD FOR THE FABRICATION THEREOF”, issued Dec. 12, 2006, and is incorporated herein by reference. Meder et al. describe a fiber optic array that includes a substrate having a fiber support surface. The array further includes an optical fiber having a fiber portion that includes an un-jacketed, un-buffered optical core segment. The un-jacketed, un-buffered optical core segment is placed in contact with the fiber support surface to orient the optical core segment at a selected position relative to the support surface. In addition, the array includes a solder glass chemically bonded to the optical core segment and the fiber support surface so that the optical core segment is secured at a predetermined location relative to the support surface of the substrate. A method for fabricating such a fiber optic array is also provided.
U.S. Patent Publication 2010/0111478 to Takaharu Fujiyama (hereinafter, “Fujiyama”) titled “NON-LINEAR FIBER ARRAY HAVING OPPOSING V-GROOVE STRUCTURES”, published May 6, 2010, and is incorporated herein by reference. Fujiyama describes a fiber array unit (FAU) having plurality of optical transmission channels (e.g., fiber optics) terminating at a side surface thereof for carrying optical signals to and/or from waveguides in a planar lightwave circuit (PLC). The optical transmission channels of the FAU terminate at the side surface thereof in a non-linear, cross-sectional pattern (e.g., a curved pattern). The non-linear pattern is determined by a pattern of grooves formed in a substrate of the FAU, in combination with a lid which may also have an inverse, non-linear pattern, to thereby rigidly, reliably and permanently hold the optical transmission channels in place.
U.S. Pat. No. 6,754,006 titled “Hybrid metallic-dielectric grating” issued Jun. 22, 2004 to Barton et al. and is incorporated herein by reference. This patent describes a diffraction grating having a metallic base layer and layers of dielectric materials of varying refractive index, where a bottom interface of the layers is adherent to the metallic base layer. The dielectric layers are periodically spaced on top of the metallic base layer, leaving the metallic base layer exposed in regions. This grating allows for the polarization-insensitive reflective properties of the base metallic layer to operate in conjunction with the polarization sensitive diffraction properties of the multilayer grating structure to provide near 100% diffraction efficiency over a reasonable wavelength bandwidth, independent of the polarization of the incident beam.
U.S. Pat. No. 5,907,436 titled “Multilayer dielectric diffraction gratings” issued May 25, 1999 to Perry et al., and is incorporated herein by reference. This patent describes the design and fabrication of dielectric grating structures with high diffraction efficiency. The gratings have a multilayer structure of alternating index dielectric materials, with a grating structure on top of the multilayer, and obtain a diffraction grating of adjustable efficiency, and variable optical bandwidth.
U.S. Pat. No. 8,355,608 (listed above) issued to Yongdan Hu on Jan. 15, 2013 with the title “Method and apparatus for in-line fiber-cladding-light dissipation,” and is incorporated herein by reference. In U.S. Pat. No. 8,355,608, Dr. Hu describes an apparatus and method for in-line cladding-light dissipation including forming a light-scattering surface on the optical fiber such that the light-scattering surface scatters cladding light away from the optical fiber. In some embodiments, the apparatus includes an optical fiber having a core and a first cladding layer that surrounds the core, wherein a first portion of the optical fiber has a light-scattering exterior surface. Some embodiments further include a transparent enclosure, wherein the transparent enclosure includes an opening that extends from a first end of the transparent enclosure to a second end of the transparent enclosure, and wherein at least the first portion of the optical fiber is located within the opening of the transparent enclosure. Some embodiments include a light-absorbing housing that surrounds the optical fiber and the transparent enclosure and is configured to absorb the light scattered away from the optical fiber by the light-scattering exterior surface.
U.S. Pat. No. 6,768,850 issued to Dugan, et al. on Jul. 27, 2004 with the title “Method of index trimming a waveguide and apparatus formed of the same” and is incorporated herein by reference. In U.S. Pat. No. 6,768,850 Dugan et al. describe a method of using a beam of ultra-short laser pulses, having pulse durations below 10 picoseconds, to adjust an optical characteristic within an optical medium is provided. The beams would have an intensity above a threshold for altering the index of refraction of a portion of the optical medium. The beams could be selectively applied to the optical medium and any structures formed or existing therein. Thus, the beam could be moved within a waveguide in the optical medium to alter the index of refraction of the waveguide forming any number of different longitudinal index of refraction profiles. The beam could also be moved within the optical medium near the waveguide to alter an effective index of refraction of a signal traveling within the waveguide.
U.S. Pat. No. 7,517,159 issued to Rolston et al. on Apr. 14, 2009 with the title “Two substrate parallel optical sub-assembly” and is incorporated herein by reference. In U.S. Pat. No. 7,517,159, Rolston et al. describe an optical assembly and a method for assembling components of the optical assembly, the method including providing a structure for guiding light; providing a plurality of optical fibers embedded in a fixed arrangement in the structure, the optical fibers for coupling the light from a coupling surface the structure; abutting a first package against the coupling surface, such that each one of multiple elements comprised in the first package is substantially aligned with each one of a first group of optical fibers in the plurality of optical fibers; and abutting a second package against the coupling surface, adjacent to the first package, and such that: the first and the second package are spaced apart by a gap; and each one of multiple elements comprised in the second package is substantially aligned with each one of a second group of optical fibers in the plurality of optical fibers, the gap providing a tolerance in a position of any one of: each one of the elements in the packages; the packages with respect to each other, and each one of the packages with respect to the structure.
U.S. Pat. No. 7,522,807 issued to Rolston et al. on Apr. 21, 2009 with the title “Optical connector assembly” and is incorporated herein by reference. In U.S. Pat. No. 7,522,807, Rolston et al. describe a coupling for at least one optical fiber with an optoelectronic device. The apparatus includes at least one v-groove for receiving at least one optical fiber. A first end of the apparatus is then polished at a predetermined angle in order to enable an optical coupling with the optoelectronic device.
U.S. Pat. No. 7,537,394 issued to Rolston et al. on May 26, 2009 with the title “Method for assembling a two substrate parallel optical sub-assembly” and is incorporated herein by reference. In U.S. Pat. No. 7,537,394, Rolston et al. describe an optical assembly and a method for assembling components of the optical assembly, the method including: providing a structure for guiding light; providing a plurality of optical fibers embedded in a fixed arrangement in the structure, the optical fibers for coupling the light from a coupling surface the structure; abutting a first package against the coupling surface, such that each one of multiple elements in the first package is substantially aligned with each one of a first group of optical fibers in the plurality of optical fibers; and abutting a second package against the coupling surface, adjacent to the first package, and such that: the first and the second package are spaced apart by a gap; and each one of multiple elements in the second package is substantially aligned with each one of a second group of optical fibers in the plurality of optical fibers, the gap providing a tolerance in a position of any one of: each one of the elements in the packages; the packages with respect to each other, and each one of the packages with respect to the structure.
There is a need for an improved coupler for launching light from a plurality of optical fibers into a photonic chip (as well as for launching light from a photonic chip into a plurality of optical fibers) for such uses as data transmission and communications, optical networking, photonics, optical computing, generation of laser seed light signals of different wavelengths, and combining laser signals.